2000 Isuzu Trooper

That is an egr valve fault, that means its dirty, and the hose that is connected to it may be dirty, along with the intake manifold.

I would try doing a top engine cleaning aside from cleaning the egr valve.

A top engine cleaning is when you take a bottle of seafoam and methodically pull it through the vacuum system, prefferably a small vacuum hose.

What it does is(depending how dirty your system is) it will clean all the built up carbon etc, and burn it through the combustion system, the vehicle remains running as you do this, and you must keep the your fingers on the throttle plate so that the car doesnt shut off and keep a minimum of the seafoam going in at one time to avoid lock up. I dont know if that could even happen, because this stuff will evaporate on contact with heat, but I never gave it the option to happen. Its an awesome trick, and your vehicle will feel brand new. But if you've never done it, I would try to get someone who has some experience with it so that we dont have the potential for lock up

A lot of people say the brake booster, but I dont like using that, because your unable to pinch it off if need be, you I like to use the pcv vavle hose, or like you said the egr hose

Id also like to remind you that you will see a lot of black smoke coming from the exhaust, that is only burnt up carbon, it should be clean by the time you finish, no more black smoke